Fingernail enamel composition



Patented Apr. 2, 1940 PATENT OFFICE FINGERNAIL ENAMEL COMPOSITION Richard 0. Peter, mun, N. 1., assignor to n. r. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application July 8, 1931. Serial No. 152,533

This invention relates to fingernail enamel compositions which afiord desirable improvements with respect to working properties, appearance and general durability.

Conventional fingernail enamels, especially those containing substantial quantities of cellulose nitrate are frequently characterized by an undesirable tendency to shrink during drying and to peel at the edge of the nail. Although it is 10 evident that a maximum content of solid material at a workable viscosity is desired in order to provide adequate build and gloss, the concentration should not be so high that the flowing and drying qualities are impaired, yielding films 1 which are not sufliciently smooth to be practicable. Heretofore it has been the practice to restrict a nail enamel composition to substantially only cellulose nitrate as the solid bodyproducing material in order to obtain a quickdrying enamel, and as a result the important properties of smoothness, flexibility and adhesion are sacrificed. Previously available fingernail enamelsalso possess an undesirable characteristic known as .bodying which is a gradual thick- 3 ening of the enamel by evaporation of the volatile ingredients, when the enamel is stored in poorly stoppered containers. The teachings of the present invention provide for the production of a fingernail enamel wherein the several defects of such products previously available are eliminated.

It is an object of this invention toprovide an enamel which when applied to fingernail and like surfaces afiords a clear, smooth film of sua perior flexibility and adhesion. Another object is the provision of a fingernail enamel which is characterized by improved gloss and greater durability from the standpoint of abrasion resistance and freedom from cracking and peeling 4p tendencies. Another object of the invention is the provision of a fingernail enamel which is.

characterized by absence of discoloration when exposed to light during storage in bottles or after application to the nail. A further object is the 45' provision of a nail enamel composition which is stable with respect to dye-tinting and pigmentation. A still further object of the invention is the provision of a fingernail enamel composition 7 which, when stored in poorly stop r-ed con- 50 tainers, does not substantially "body up" by an increase in viscosity with evaporation of the volatile ingredients. Other objects will become apparent as the description of the invention pro-' ceeds.

These objects are accomplished by the utilization of a specific class of resins consisting of polymerization products of acrylic acid and acrylic acid derivatives in cellulose nitrate compositions as hereinafter more fully described.

By way of illustration but not by way of lim- 1o itation, the following examples are given in aceordance with the present invention:

Example 1 Per cent Cellulose nitrate 3.2 1

The plasticizer used in the compositions of Examples 1 and 2 consisted of the phthalate ester of a mixture of synthetic higher alcohols 40 of four or more carbon atoms obtained during the synthesis of methanol as prepared by the catalytic hydrogenation of carbon monoxide at elevated temperatures and high pressures as described in U. S. Patent Nos. 1,820,417 and 1,844,- 5 857. The mixture of alcohols from which the ester is manufactured includes normal propanol, isobutanol, 2-methyl butanol-l, 3-methyl butano1-2, 2, 4-dimethyl pentanol-B, 3-methyl pentanol-2, i-methyl hexanol-l, i-methyl hepso tanol-l, and higher alcohols. The phthalate ester may be conveniently manufactured by conventional esterification methods utilizing phthalic anhydride or it may be prepared by ester interchange as described in U. S. Patent No. 1,993,552. This plasticizer was found to have particular merit in the present compositions because of the superior water resistance afforded in its use.

Example 3 Per cent Cellulose nitrate 3.2 Denatured alcohol 2B 1.4 Butyl acetate 7'7. 2 Propyl methacrylate resin 15. Diamyl phthalate 3. 2

Example 4 I Per cent Cellulose nitrate 9.4 Denatured alcohol 2B 4. 0 Isobutyl acetate 73.6 Isobutyl methacrylate resin 9. 6 Tricresyl phosphate 3. 4

The viscosity characteristic of the cellulose nitrate used in the above examples is about 3 seconds as determined in accordance with procedure outlined in A. S. T. M. specifications D-301-33, Formula B. While a cellulose nitrate of about this viscosity characteristic is preferred, cellulose nitrates of somewhat higher or even lower viscosities may be utilized by suitable adjustments in the ratios of the other film-forming ingredients.

Denatured alcohol 23, introduced by the alcohol-wet cellulose nitrate of commerce, is 11.8. Internal Revenue Bureau formula which is composed of 100 gallons of 95% by volume ethyl alcohol to which has been added A; gallon of benzol. Other commercially available denatured alcohols are likewise suited for the present compositions provided they do not impart a disagreeable odor to the product.

Examples 2, 3 and 4 are of particular importance since in these compositions, bodying tendencies which characterize previously available fingernail enamels are markedly reduced. The composition of Example 2 has the further advantage in that it may be applied directly over a dried film of a previously applied fingernail enamel without causing lifting of the first coating. The general utility of these and equivalent solvent and solvent-diluent compositions in fingernail enamels is disclosed in co-pending applications S. N. 152,532 and S. N. 152,534. The primary requirement for these ingredients is that they have an evaporation rate approximately equal to that of butyl acetate.

The resin constituent of the new compositions is preferably a polymerization product of propyl, butyl or isobutyl methacrylate, although the higher aliphatic and alicyclic alcohol polymers, such as hexyl, heptyl, octyl, lauryl, cetyl, allyl, methoxyethanol, cyclohexyl and methoxycyclohexyl alcohol esters of methacrylic acid, and the corresponding ester polymers of acrylic acid are likewise suited. In general, polymerized esters of an acrylic acid, the acid being represented by the general formula OHr-O-COOH where R is hydrogen or an alkyl radical, may be used.

The methyl and ethyl methacrylate compounds are relatively impractical for use in the cellulose nitrate compositions of the present invention because of the excessively high viscosities whichcharacterize these combinations. In addition, the degree of wear and abrasion resistance secured from compositions based on these resins is not as great as when the higher alcohol esters are employed.

The preparation of monomeric acrylic acid esters is described in the co-pending application of D. J. Loder, Serial No. 593,411. The polymerization of the esters is effected by well-known methods, as for instance with the aid of light, heat or a suitable catalyst, such as an organic peroxide.

Other plasticizers which may be employed in the compositions of this invention include dibutyl, dihexyl, diheptyl, dioctyl phthalates, tributyl' phosphate, dibutyl tartrate, methoxy ethyl phthalate, etc.

The solvent vehicle of the present invention consists of not less than '75 per cent of the preferred composition, and is preferably selected. from a group of solvents of medium volatility which will produce a coating of adequate smoothness, free from turbidity and coloration. High boiling solvents are eliminated in the preparation of this type of nail enamel because of their slow rate of evaporation. The more volatile solvents are generally not preferred due to their more rapid evaporation causing an orange peel surface.

Optimum conditions for securing the outstanding qualities which characterize this improved nail enamel are obtained when the cellulose nitrate-resin-plasticizer ratios are within the range of 10-10-4 and 10-50-10 parts by weight, although satisfactory results in build, clarity, gloss and durability are also obtained somewhat beyond the upper limit of the resin proportion shown. Also some improvements are apparent when the resin proportion is reduced to a ratio of 10-5-2 or even lower, but the range indicated above is much preferred.

The resins of the present invention have been found to be of particular merit in fingernail enamel compositions. They do not materially increase the viscosity of the enamel, and hence permit the building up of a high solids content which in turn allows a lower concentration of cellulose nitrate thereby eliminating undesirable shrinkage tendencies and separation of the film from the fingernail surface. The tendency of bodying when stored in poorly stoppered containers such as is experienced with the conventional fingernail enamels, is substantially reduced when the preferred solvent compositions as previously indicated 'are employed.

The severalingredients of fingernail enamel compositions of the invention are thoroughly and uniformly blended by ordinary mixing processes. The final compositions fiow freely and are easily applied to the finger or toe nail with a. soft brush. 0n drying a clear, odorless, transparent film results. The coating does not discolor during exposure and wear. Dyes or pigments which are commonly incorporated in nail enamels are unaffected by the improved vehicle. The enamels afford excellent adhesion, and are remarkably resistant to soapy water, alkali, marring and scratching. These durable compositions are characterized by extraordinarily hi h solids for 1| a given viscosity, thus providing the requisite gloss and build with one-application.

. It is apparent that many widely different'embodiments of this invention may be made without departing from the spirit and scope thereof; and, therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A fingernail enamel composition comprising cellulose nitrate, a plasticizer'and. a polymerized organic derivative of an acrylic acid selected from the group consisting of aliphatic and alicyclic esters of an acrylic acid.

2. Composition of claim 1 in which the acrylic acid is represented by the general formula om-c-ooon acrylate polymer is derived from propyl alcohol.

5. Composition of c1aim3 in which the methacrylate polymer is derived from 'isobutyl alcohol. 6. Composition of claim 1 in which the .ratio of cellulose nitrate to resin polymer to plasticizer lies between 10-50-10 .and 10-5-2 parts by weight.

7. A fingernail enamel composition consisting of cellulose nitrate, a plasticizer, a polymerized organic derivative of an acrylic acid selected from the group consisting of aliphatic and allcyclic estersof an acrylic acid and a liquid volatile vehicle consisting substantially of a liquid. volatile solvent having an evaporation rate approximately equal to that of butyl acetate.

8. A fingernail enamel composition consisting of cellulose nitrate, a plasticizer, a polymerized organic derivative of an acrylic acid selected from the group consisting of aliphatic and alicyclic esters of an acrylic acid and a liquid volatile vehicle consisting substantially of a solvent-diluent mixture having an evaporation rate approximately equal to that of butyl acetate.

9. A fingernail enamel having approximately the following composition:

. Percent Cellulose nitrate 3.2 Denatured alcohol 1.4 Butyl aceta 38.6 Petroleum naphtha 38.6 Resin (propyl methacrylate polymer) 15.0

RICHARD C. PETER. 

